• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.38.1-38.1
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• 2013

We present observational estimation of the infrared (IR) luminosity function (LF) of local (z < 0.3) star-forming (SF) galaxies derived from the AKARI NEP-Wide samples. We made an analysis of the NEP-Wide data with optical spectroscopic information allowing an accurate determination of luminosity function. Spectroscopic redshifts for about 1650 objects were obtained with MMT/Hectospec and WIYN/Hydra, and the median redshifts is about 0.22. To measure the contribution of SF galaxies to the luminosity function, we excluded AGN sample by comparing their SEDs with various model template. Spectroscopic redshifts and the AKARI's continuous filter coverage in the mid-IR (MIR) wavelength (2 ~ 25 micron) enable us to avoid large uncertainties from the mid-IR SED of galaxies and corresponding k-corrections. The 8-micron luminosity function shows a good agreement with the previous works in the bright-end, whereas it seems not easy to constrain the faint-end slope. The comparison with the results of the NEP-Deep data (Goto et al. 2010) suggests the luminosity evolution to the higher redshifts, which is consistent with the down-sizing evolutionary pattern of galaxies.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.135-139
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• 2017

We have performed systematic studies of the properties of dust in various environments of nearby galaxies with AKARI. The unique capabilities of AKARI, such as near-infrared (near-IR) spectroscopy combined with all-sky coverage in the mid- and far-IR, enable us to study processing of dust, particularly carbonaceous grains includings polycyclic aromatic hydrocarbons (PAHs), for unbiased samples of nearby galaxies. In this paper, we first review our recent results on individual galaxies, highlighting the uniqueness of AKARI data for studies of nearby galaxies. Then we present results of our systematic studies on nearby starburst and early-type galaxies. From the former study based on the near-IR spectroscopy and mid-IR all-sky survey data, we find that the properties of PAHs change systematically from IR galaxies to ultraluminous IR galaxies, depending on the IR luminosity of a galaxy or galaxy population. From the latter study based on the mid- and far-IR all-sky survey data, we find that there is a global correlation between the amounts of dust and old stars in early-type galaxies, giving an observational constraint on the origin of the dust.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.15-23
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• 2016

A study was conducted to evaluate the effects of irrigation (amount, interval) on tree growth, fruit quality, and cracking of organic 'Campbell Early' grapevine in 2012 and 2013. Three irrigation treatments were applied using a sprinkler system from mid-June to mid-August in 2012 and 2013, as follows: 10 mm was applied daily (10 mm-IR), 20 mm was applied every two days (20 mm-IR), and 30 mm was applied every five days (30 mm-IR). Soil electrical conductivity (EC) and temperature were found to be greatest in the 10 mm-IR treatment in both years. Soil moisture content ranged between 20-40% in the 10 mm-IR, between 20-60% in the 20 mm-IR, and between 20-70% in the 30 mm-IR treatment plots. The total number of leaves per shoot and shoot growth were found to be greatest in the 20 mm-IR and 30 mm-IR treatments, respectively. Cluster and berry weights, and cluster and berry sizes were not consistently affected by the treatments. The 10 mm-IR treatment resulted in an increase in fruit SSC, SSC/acidity ratio, and berry skin pigmentation ($b^*$; blue). Approximately 5% of fruit cracking was observed on average over both years in the 10 mm-IR-treated fruit, while the 30 mm-IR treatment resulted in nearly 18% of cracking in 2012. Average marketable fruit yield per year over two years was greatest for the 10 mm-IR treatment ($24.4t{\cdot}ha^{-1}$) followed by the 30 mm-IR treatment ($22.7t{\cdot}ha^{-1}$) and lastly the 20 mm-IR treatment ($22.2t{\cdot}ha^{-1}$). Thus, the 10 mm-IR treatment represents a suitable irrigation regimen for controlling leaf and shoot growth of vines grown under a rain-shelter system in sandy loam soils, while improving fruit sugar contents and skin color and limiting fruit cracking.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.321-324
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• 2012

Using extensive mid-IR datasets from AKARI, i.e. 9-band photometry covering the wavelength range from $2{\mu}m$ to $24{\mu}m$ and the unbiased spectroscopic survey for sources with $S_{\nu}$($9{\mu}m$)>0.3 mJy, we study starburst galaxies specifically at the redshift of z ~ 0.5, whose mid-IR spectra are clearly dominated by the PAH emission features. PAH-selected galaxies, selected with extremely red mid-IR colour due to PAHs, have high rest-frame PAH-to-stellar luminosity ratios, comparable to those in the most active regions in nearby starburst galaxies. Thus, they seem to have active starburst regions spreading over the whole body. Furthermore, some of PAH-selected galaxies are found to have peculiar rest-frame 11-to-$8{\mu}m$ flux ratios, which is systematically smaller than nearby starburst/AGN spectral templates. This may indicate a systematic difference in the physical condition of ISM between nearby and distant starburst galaxies.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.29-31
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• 2017

We plan to produce a faint source catalogue from the AKARI mid-infrared (IR) all-sky diffuse maps. In the publicly-available AKARI mid-IR point source catalogue (PSC), sources were extracted from single-scan images, and confirmed by using the other scan images. By stacking multiple scan images, we can detect fainter sources which are not listed in the PSC. We optimized the source extraction process using a $6^{\circ}{\times}6^{\circ}C$ area around the star-forming region, Cepheus B. Then, we divided the all-sky data into three seasonal images, and checked the positions and the fluxes of the detected sources on the images. As a result, our new source extraction method works well; 90% of the sources are also identified in the WISE catalogue. In this method, we obtain the detection limit twice deeper than that of the PSC. The number of sources increases by a factor of 2, as compared with the PSC.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.865-872
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• 2002

A systematic way of determining the equilibrium orientation of carbon monoxide (CO) in heme proteins using time-resolved polarized mid-IR spectroscopy is presented. The polarization anisotropy at pump-probe delay time of zero in the limit of zero photolysis and the angular distrbution function of CO are required to obtain the equilibrium orientation of CO. An approach is developed for determining the polarization anisotropy in the zero-photolysis limit from the anisotropy measured under finite photolysis conditions in an optically thick sample where the fraction of molecules photolyzed decreased as the pump pulse passes through and is absorbed by the sample. This approach is verified by measuring the polarization anisotropy of CO of carbonmonoxy myoglobin at various levels of photolysis. This method can be readily applied to other photoselection experiments determining precise angle between transition dipoles.

• Proceedings of the Korea Crystallographic Association Conference
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• 2000.05a
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• pp.30-30
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• 2000

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.41.2-41.2
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• 2015

We have performed deep wide-field CCD photometry of the young open cluster IC 1805 in the famous star forming region W4, and obtained photometric data for more than 91,000 stars in the field of IC 1805 based on observations with the 3.6m CFHT and the AZT-22 1.5m telescope at Maidanak Astronomical Observatory in Uzbekistan. The photometric data cover an area $43^{\prime}{\times}45^{\prime}$ which is far larger and far deeper than any other optical observations made for the cluster. In order to select the young stellar objects with mid-IR excess emission, we have performed mid-IR photometry of the cluster using the archival images obtained with the Spitzer Space Telescope IRAC and MIPS instruments. From a preliminary analysis of the data, we determined the reddening law ($R_V=3.02{\pm}0.05$), distance modulus ($V_0-M_V=11.9{\pm}0.2$), and the spatial distribution of members.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.101-105
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• 2019

ZnS substrates with excellent transmittance in the mid-infrared region ($3-5{\mu}m$) were prepared using hot pressing instead of conventional chemical vapor deposition (CVD). Diamond-like carbon(DLC) was coated on either one or both sides of the ZnS substrates to improve their mechanical properties and transmittance. More specifically DLC was coated using CVD with an Ar and $C_2H_2$ mixed gas, and Ge was used as the bonding layer. During CVD, the bias voltage was fixed to 500 V and analyzed by Fourier transform infrared spectroscopy (FT-IR), nanoindenter, scanning electron microscope and energy dispersive spectrometry. Results of hardness analysis using the nanoindenter, showed that DLC coating increased from 5.9 to 17.7 GPa after deposition. The FT-IR spectroscopy results showed that, in the mid-infrared region ($3-5{\mu}m$), the average transmittance of the samples with DLC coating on one and both sides increased by approximately 6% and approximately 11.2% respectively. In conclusion, the DLC coating improved the durability and transmittance of the ZnS substrates.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.52.1-52.1
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• 2010

The Japanese infrared (IR) space mission AKARI monitored the brightness in the fields very close to the north ecliptic pole (NEP) with nine wavebands in Infrared Camera (IRC), which cover the wavelength range from 2 to $24{\mu}m$. We reduced the NEP monitor observations and examined the smoothness of the sky background brightness. Our analysis shows that the background brightness is smooth over a frame of about $10'\times10'$ within about 0.1% deviation in mid-IR. Because the zodiacal light (ZL) and emission (ZE) dominate the diffuse sky brightness in the near- and mid-IR wavelengths, the background brightness varies with season through a year. We tried sinusoidal fittings to the observed NEP background brightness. The fitting analysis shows that the sine function is successful in describing the seasonal variation of the ZL and ZE within 2% deviations from the observed brightness, especially for the 15, 18, and $24{\mu}m$ bands, within 0.3%. These results will provide limits and caveats for the studies of the cosmic infrared background radiation.